When the salt starts to pop (from the water trapped in the salt crystal), slap down your burger, dimple side up.
late 15c., "strike with the open hand," from slap (n.). As an adverb, 1670s, "suddenly;" 1829, "directly." Related: Slapped; slapping.
mid-15c., probably of imitative origin, similar to Low German slappe, German Schlappe. Figurative meaning "insult, reprimand" is attested from 1736. Slap-happy (1936) originally meant "punch-drunk." Slap on the wrist "very mild punishment" dates from 1914.
Precisely; directly: Streets that ended slap in a courtyard/ The storm was pointed slam-bang at Tampa (first form 1829+, second 1885+, third 1940s+)